Visual-to-Code: The Evolution of Application Modernization in 2025

The "Big Bang" rewrite is a $3.6 trillion suicide mission. Every year, enterprise leaders authorize massive budget allocations to replace legacy systems, only to see 70% of those projects fail to meet their original goals or exceed their timelines by years. The problem isn't a lack of talent; it's a lack of visibility. You cannot modernize what you do not understand, and in 2025, the industry is finally moving away from manual code archaeology toward a "Visual-to-Code" paradigm.

TL;DR: Visual-to-Code: The Evolution of modernization replaces manual "code archaeology" with visual reverse engineering, allowing teams to record user workflows and automatically generate documented React components, cutting modernization timelines from 18 months to mere weeks.

The Archaeology Problem: Why 67% of Systems Lack Documentation#

For decades, the standard operating procedure for modernization has been "The Great Discovery." This involves high-priced consultants spending six months reading undocumented COBOL, Java, or legacy .NET code to figure out what the system actually does.

Statistics show that 67% of legacy systems lack any form of current documentation. When you combine this with the fact that the original architects have likely retired, you are left with a "black box" that runs your most critical business processes. This is where the 18-24 month rewrite timeline comes from—12 months of that is just trying to understand the current state.

The Cost of Manual Extraction#

When an engineer manually recreates a legacy screen in a modern framework like React, the process is grueling:

1. •Inspect the DOM or legacy UI components.
2. •Reverse engineer the state management.
3. •Identify API endpoints (often undocumented).
4. •Re-write the CSS/styling to match modern design systems.
5. •Write E2E tests to ensure parity.

On average, this takes 40 hours per screen. In a 500-screen enterprise application, that is 20,000 man-hours—roughly 10 years of effort for a single developer.

The Visual-to-Code Evolution#

The evolution of application modernization in 2025 is defined by Visual Reverse Engineering. Instead of reading code to understand behavior, we record the behavior to generate the code.

By using Replay, developers record a real user performing a workflow—like processing an insurance claim or opening a brokerage account. Replay captures the UI state, the network calls, and the business logic transitions. It then transforms that recording into documented, production-ready React components and API contracts.

💰 ROI Insight: Companies using Replay reduce the time spent per screen from 40 hours to just 4 hours. For a mid-sized application, this represents a direct saving of over $1.2M in engineering salaries alone.

Step-by-Step: The New Modernization Workflow#

Modernizing a legacy system no longer requires a "scorched earth" policy. Here is how enterprise architects are utilizing the Visual-to-Code evolution.

Step 1: Automated Technical Debt Audit#

Before writing a single line of code, you must quantify the mess. Replay’s AI Automation Suite scans the legacy environment to identify redundant components and dead code paths. This prevents "garbage in, garbage out" during the migration.

Step 2: Recording the "Source of Truth"#

The user interface is the only living documentation of how a legacy system actually functions. Developers or QA teams record the "Golden Path" workflows.

• •The Library: Replay extracts styles and UI elements into a centralized Design System.
• •The Flows: Replay maps the architectural relationships between screens and services.

Step 3: Visual Extraction to React#

Replay takes the recording and generates a "Blueprint." This is an editable, visual representation of the component logic. From here, Replay generates clean, typed React code.

typescript
// Example: Generated component from Replay Visual Extraction
// Source: Legacy Insurance Claims Portal (v2008)
// Target: Modern React + Tailwind + TypeScript

import React, { useState, useEffect } from 'react';
import { Button, Input, Card } from '@/components/ui';
import { useClaimsApi } from '@/hooks/useClaimsApi';

interface ClaimData {
  claimId: string;
  policyNumber: string;
  status: 'PENDING' | 'APPROVED' | 'REJECTED';
  amount: number;
}

export const LegacyClaimFormMigrated: React.FC<{ id: string }> = ({ id }) => {
  const [data, setData] = useState<ClaimData | null>(null);
  const { fetchClaim, updateClaim } = useClaimsApi();

  // Logic preserved from legacy workflow recording
  useEffect(() => {
    async function load() {
      const result = await fetchClaim(id);
      setData(result);
    }
    load();
  }, [id]);

  const handleApprove = async () => {
    if (!data) return;
    // Replay identified this specific state transition from the video capture
    await updateClaim({ ...data, status: 'APPROVED' });
  };

  if (!data) return <div>Loading legacy context...</div>;

  return (
    <Card title={`Claim: ${data.claimId}`}>
      <div className="grid grid-cols-2 gap-4">
        <Input label="Policy #" value={data.policyNumber} readOnly />
        <Input label="Amount" value={`$${data.amount}`} readOnly />
      </div>
      <div className="mt-4 flex gap-2">
        <Button onClick={handleApprove} variant="primary">
          Approve Claim
        </Button>
      </div>
    </Card>
  );
};

Step 4: Generating API Contracts and E2E Tests#

Modernization isn't just about the frontend. Replay analyzes the network traffic recorded during the session to generate:

1. •OpenAPI/Swagger Specs: Documenting the legacy endpoints that the new frontend must communicate with.
2. •Playwright/Cypress Tests: Ensuring the new component behaves exactly like the legacy recording.

⚠️ Warning: Do not attempt to modernize the backend and frontend simultaneously. Use the Visual-to-Code approach to decouple the UI first, then use the generated API contracts to strangle the legacy backend services.

Architecture Mapping: From Black Box to Blueprints#

One of the greatest risks in legacy modernization is missing the "hidden" logic—the weird edge case where clicking a checkbox on page 2 changes a validation rule on page 5.

Manual documentation misses these. Replay’s Flows feature visualizes the entire application architecture based on real usage. It builds a graph of every state transition, API call, and component dependency.

The "Blueprints" Editor#

Within Replay, the "Blueprints" act as a bridge between the visual recording and the final code. Architects can modify the logic visually before the code is exported. This allows for:

• •Logic Consolidation: Merging three different legacy "Save" functions into one modern service.
• •Security Injection: Automatically adding Auth0 or Okta wrappers to components that previously had no modern authentication.
• •Accessibility (a11y) Upgrades: Automatically injecting ARIA labels into components that were built before modern web standards.

typescript
// Example: Replay-generated API Contract for legacy integration
// This ensures the modern React app can talk to the mainframe/monolith

/**
 * @generated by Replay AI Automation Suite
 * Legacy System: Healthcare Provider Portal
 * Endpoint: /api/v1/patient/records
 */

export interface PatientRecordRequest {
  providerId: string; // Extracted from session context
  patientId: string;  // Extracted from URL parameter
  timestamp: string;  // Format matched to legacy ISO-8601 variant
}

export interface PatientRecordResponse {
  id: string;
  records: Array<{
    date: string;
    diagnosisCode: string; // Mapping ICD-9 to ICD-10 logic preserved
    notes: string;
  }>;
}

Built for Regulated Industries#

The Visual-to-Code evolution isn't just for startups. Replay was built for the most stringent environments:

• •Financial Services: Modernizing core banking systems without exposing PII.
• •Healthcare: HIPAA-ready workflows that redact sensitive patient data during the recording and extraction process.
• •Government/Defense: On-premise deployment options for air-gapped modernization projects.

📝 Note: Replay does not require your source code to be uploaded to a cloud. The extraction happens via the visual layer, and the platform can be hosted entirely within your VPC (Virtual Private Cloud).

Why the Future is Understanding, Not Rewriting#

The mantra of the 2010s was "Move fast and break things." In the 2020s, for an Enterprise Architect, that mantra is a recipe for a pink slip. The goal is now "Understand fast and modernize safely."

The $3.6 trillion technical debt problem isn't going away by hiring more developers to write more code. It goes away when we use AI and visual reverse engineering to bridge the gap between what a system is and what it needs to be.

Replay represents the shift from manual archaeology to automated insight. By treating the user interface as the "source of truth," we bypass the messy, undocumented, and often terrifying legacy codebase, extracting only the value that matters to the business.

Frequently Asked Questions#

How long does legacy extraction take with Replay?#

A typical enterprise screen, which would take a senior developer 40 hours to manually audit, design, and code in React, takes approximately 4 hours with Replay. A full application module (20-30 screens) can be moved from "Black Box" to "Documented Codebase" in under two weeks.

What about business logic preservation?#

Replay doesn't just "screenshot" the UI. It records the underlying state changes and network requests. If a legacy button triggers a complex validation sequence, Replay captures that logic flow and reflects it in the generated React hooks and service layers.

Does Replay work with desktop legacy apps?#

Yes. Replay supports web-based legacy systems (JSP, ASP.NET, Silverlight, etc.) as well as desktop-to-web migrations via our specialized capture agents.

Is the generated code maintainable?#

Unlike "low-code" platforms that output spaghetti code, Replay generates clean, human-readable TypeScript and React. It follows your organization's specific coding standards and uses your existing Design System components.

How does this handle security in regulated industries?#

Replay is SOC2 compliant and HIPAA-ready. We offer an on-premise version for organizations that cannot use cloud-based tools. During the recording process, sensitive data can be automatically masked or redacted before it ever hits the Replay engine.

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Ready to modernize without rewriting? Book a pilot with Replay - see your legacy screen extracted live during the call.